We are investigating a new experimental approach for the treatment of recurrent malignant brain tumors which utilizes a new class of anti- cancer compounds, called targeted protein toxins. A targeted protein toxin is a compound that consists of two parts. The binding moiety targets the conjugate to the surface of tumor cells bearing the appropriate antigen or receptor and toxin moiety then penetrates the cell membrane and inactivates protein synthesis, resulting in cell death. The specific compound under investigation in this trial, transferrin-CRM 107 (Tf-CRM 107), is a conjugate of human transferring (Tf) and diphtheria toxin (DT) with a point mutation (CRM 107). The binding moiety, Tf, binds to the transferrin receptor which helps cells take up iron and is present in higher number on tumor cells than on normal brain cells. The complete compound, Tf-CRM 107, can kill tumor cells preferentially at low concentration, and when directly injected into tumors, causes tumor shrinkage in animal models of primary human malignant brain tumors. We have initiated a phase I trial of regional therapy with Tf-CRM 107 treat recurrent malignant brain tumors. In this clinical trial, Tf-CRM 107 will be delivered by slow intratumoral and peritumoral infusion. The purpose of this study is to determine if this new experimental compound, Tf-CRM 107, can be used safely in patients with malignant brain tumors. We also hope to learn about its ability to kill tumor cells in patients with malignant brain tumors.